On the residential side subcontractor rule-of-thumb which includes equipment, material, labor, overhead and profit for an economy job with 1 or 2 coats and little brushwork: $1.90 perSFof floor area
Good Quality, 2 or 3 coats: $4.35 perSFof floor area

Again, there are a lot of variables like how much trim and whether or not there are different colors, etc. But, maybe this helps.